In fuel systems, valves, characterized as "demand" valves, maintain fuel supply lines closed except when a utility such as a furnace is using fuel and a reduced pressure in the supply line on the utility side causes a diaphragm controlling the valve to open the valve. Similarly, pressure regulator valves which are diaphragm controlled, rather than using a solid piston, will be controlling the flow of inflammable fluid which will be in contact with the flexible diaphragm.
These control diaphragms are made from a material that is resistant to hydrocarbons and yet the constant flexing might cause a breach which could result in a leak of the hydrocarbon to the surrounding environment. Diaphragms need atmospheric venting on one side and thus cannot be totally sealed off.
The present invention has an object, the provision of a diaphragm-controlled valve which has a safety design to avoid leakage of the fluid being controlled. It is a further object to provide a safety valve for inflammable fluids which is relatively inexpensive to manufacture.
Other objects and features of the invention will be apparent in the following description and claims in which the principles of the invention are set out together with details to enable persons skilled to make and use the invention.